Effect of morphactin (chlorfluorenol IT 3456) on the mitotic activity and cell growth in roots of Pisum sativum L.

Abstract

Morphactin in a concentration of 100 ppm does not retard pea root growth, however, it reduced the frequency of cell division and shifted the main wave of mitoses in the 24 h period from 1 to 2 mm of root segment. The mean cell cycle duration is prolonged from 14 h in the control to 22 h in morphactin-treated roots. In the presence of morphactin the decrease of <sup>3</sup>H-thymidine incorporation and diminution of labelling index is accompanied by reduction of the nuclear surface area. The described changes are not accompanied by shortening of cell length. The results obtained suggest that morphactin disturbs the mechanisms regulating the initiation of S phase and its regular course. Moreover, it inhibits the endomitotic replication of DNA.